1. Field of the Invention
This invention relates to an automatic fluid control device, particularly of the type used to control the flow of fluid fertilizer in a fertilizer application system.
2. Description of the Prior Art
A fertilizer application system normally includes a fertilizer supply tank; a tractor-drawn implement such as a cultivator, tool bar or other implement suitable for fertilizer application; a supply hose leading from the supply tank to a flow meter valve mounted on the implement; pipe and hose apparatus affixed to the implement and used to convey fluid fertilizer from the flow meter valve to the point of application; and lifting means attached to the tractor and/or the implement suitable for raising and lowering the implement or the application elements thereof between a raised, travel position and a lowered, application position.
The basic problem of control of fluid fertilizer in such a system is simply defined. Control should be such that the flow of fertilizer can be switched on when the fertilizer application elements are in position in the soil at the proper depth; conversely, when the application elements are not in the soil, the flow of fertilizer should be shut off to avoid waste and the escape of noxious chemicals into the atmosphere. In the past, flow control has been achieved by a variety of means, including rope controls, electric controls and hydraulic controls affixed to the flow meter valve. While many prior art devices do not provide automatic control in response to the raising and lowering of application elements, at least one such automatic device is known (Tanke, U.S. Pat. No. 3,044,712). Both devices which are integral to a fertilizer application implement (e.g., Tanke, U.S. Pat. No. 3,044,712) and devices which are retrofitted onto existing equipment (e.g., Ahlers, et al., U.S. Pat. No. 3,905,523) are known. None of the prior art controls has proven to be particularly satisfactory. One basic problem is that constant on-off operation of the control mechanism and opening and closing of the flow meter valve may cause wear on the valve or its control mechanism, leading to breakage.
Electric controls often require an excessive amount of maintenance for performance and may perform poorly when the weather is cool or cold. They require hookups to be placed upon a tractor, as well as the implement to be controlled, and therefore, are not easily switched from tractor to tractor. Furthermore, the control is normally actuated by a solenoid device and shut off by a return spring mechanism, which is susceptible to breakage. Hydraulic control not only requires the addition of extra hydraulic equipment but, in the case of one-way hydraulic controls, the device may also rely on a return spring mechanism and have the same susceptibility to breakage. Finally, the rope control, the oldest control method known in the art, is the most dangerous, especially when anhydrous ammonia fertilizer is being used, because so many things can occur which prevent an operator from shutting off fertilizer flow. For example, the rope can break, or loop over and become caught on some part of the implement, or the spring mechanism used in connection with the rope can become jammed by foreign material. Finally, a rope control prevents the tractor operator from enjoying the full benefits of an enclosed cab, since the cab must normally be open to allow access to the rope control.
Most of these problems exist with the particular control device involved whether or not it is a retrofit device. However, with retrofit devices, a number of other problems can arise such as compatibility with different implements, adaptability for existing flow meters, the need for additional power sources and the need for additional operator controls. Accordingly, retrofit devices may raise as many problems as they solve.